This application claims the benefit of Korean Application No. 2002-55989, filed Sep. 14, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates, in general, to microwave ovens and, more particularly, to a microwave oven provided with a hook unit and a hook locking unit which are used to open or close a door.
2. Description of the Related Art
As is well known to those skilled in the art, a microwave oven is an appliance, which cooks food by microwaves irradiated from a magnetron into a cooking cavity, through a dielectric heating method. Thus, in order to prevent microwaves harmful to the human body from leaking out, the microwave oven is designed such that microwaves are not irradiated to the cooking cavity when the door is open, and microwaves are irradiated to the cooking cavity only when the door is closed. As such, in order to control the irradiation of microwaves, the conventional microwave oven is provided with a hook unit, a hook locking unit, and a safety device. In this case, the hook unit is mounted to the door. The hook locking unit is installed in a cabinet to engage with the hook unit. The safety device is provided in the hook locking unit, and senses whether the hook unit enters the hook locking unit or not when the door is open or closed, so as to control the power supply of the microwave oven, thus preventing microwaves from leaking out when the door is open.
As shown in FIGS. 1 and 2, the conventional microwave oven includes a hook unit 2 which is mounted to the door 1. The hook unit 2 includes a connecting member 3, an upper locking hook 4 and a lower locking hook 5. The connecting member 3 moves in a vertical direction in the door 1. The upper locking hook 4 is connected to the upper portion of the connecting member 3, and the lower locking hook 5 is connected to the lower portion of the connecting member 3. A spring 6 is installed to the lower portion of the connecting member 3 in the door 1, and downwardly pulls the hook unit 2 such that the upper and lower locking hooks 4 and 5 engage with a hook locking unit 7. The upper and lower locking hooks 4 and 5 are designed such that the bottom surfaces of their hooking parts are inclined to form inclined surfaces 4a and 5a, respectively, so the upper and lower locking hooks 4 and 5 easily disengage from the hook locking unit 7 by only pulling the door 1 forwards.
The hook locking unit 7 of the cabinet 8 is provided with upper and lower guide holes 9 and 10 which correspond to the upper and lower locking hooks 4 and 5, respectively. Upper and lower locking steps 11 and 12 are provided in the hook locking unit 7 to correspond to the upper and lower guide holes 9 and 10, and guide movements of the upper and lower locking hooks 4 and 5 to be caught by the locking steps 11 and 12, respectively. The upper and lower locking steps 11 and 12 inwardly extend from the lower edges of the guide holes 9 and 10 by predetermined lengths. Upper surfaces of the upper and lower locking steps 11 and 12 are inwardly and upwardly inclined to form guide surfaces 11a and 12a, respectively, thus guiding movements of the upper and lower locking hooks 4 and 5. The hook locking unit 7 is typically a plastic injection molded product, and is fixed, at a surface thereof, to a partition wall 8a by tightening setscrews 13. The partition wall 8a partitions the cabinet into a machine room and a cooking cavity.
Several switches 14, 15 and 16 are installed in the hook locking unit 7 to sense whether the door 1 is open or not in response to the entrance of the upper and lower locking hooks 4 and 5. The first sensing switch 14 is installed in the hook locking unit 7 at a position adjacent to the upper locking step 11, and is open or closed in response to the entrance of the upper locking hook 4. The second sensing switch 15 and the monitor switch 16 are installed in the hook locking unit 7 at positions adjacent to the lower locking step 12, and are open or closed in response to the entrance of the lower locking hook 5. In this case, the first and second sensing switches 14 and 15 sense whether the door 1 is open or not so as to control the supply of power. The monitor switch 16 functions to shut off the power supply of the microwave oven when the first and second sensing switches 14 and 15 malfunction.
When a user closes the door 1 of such a microwave oven, the upper and lower locking hooks 4 and 5 are caught by the locking steps 11 and 12 to keep the door 1 closed while the contact points of the switches 14, 15 and 16 are pressed by the locking hooks 4 and 5. Thus, power is applied to the microwave oven. At this time, microwaves are irradiated into the cooking cavity. Meanwhile, when a user pulls the door 1 to open it, the upper and lower locking hooks 4 and 5 disengage from the locking steps 11 and 12 while the switches 14, 15 and 16 are disconnected from the locking steps 11 and 12 so as to shut off the power supply. At this time, microwaves are not irradiated to the cooking cavity, thus preventing microwaves from leaking out.
However, the hook locking unit 7 of the conventional microwave oven is a plastic injection molded product, so there may occur plastic deformation of the hook locking unit 7. A screw holding unit 17 is provided at a position spaced apart from each of the locking steps 11 and 12 to hold the setscrew 13 which functions to mount the hook locking unit 7 to the cabinet. Thus, when a user pulls the door 1 to open it, the locking hooks 4 and 5 pull the locking steps 11 and 12, so there may occur slight deformation around the locking steps 11 and 12. Since such deformation makes the door 1 instantaneously and slightly open even when the contact points of the switches 14, 15 and 16 are pressed, there may occur the leakage of microwaves.
Accordingly, it is an aspect of the present invention to provide a microwave oven, which is designed to prevent a locking step from being deformed when a door is open or closed, so that switches accurately sense whether the door is open or not, thus preventing microwaves from leaking out.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and/or other aspects of the present invention are achieved by providing a microwave oven, including a hook unit mounted to a door functioning to open or close a cabinet, a hook locking unit installed in the cabinet to engage with the hook unit, a locking step provided in the hook locking unit to catch the hook unit when the hook unit enters the hook locking unit, and a sensing switch installed in the hook locking unit to sense whether the hook unit enters the hook locking unit or not, wherein a screw holding unit is provided on a predetermined portion of the locking step to hold a setscrew, the setscrew functioning to mount the hook locking unit to the cabinet.
According to the present invention, the screw holding unit is provided on an end of the locking step at which the hook unit is caught by the locking step.
Furthermore, the screw holding unit includes a cylindrical boss integrated with the locking step, and a threaded hole formed along a central axis of the cylindrical boss to engage with the setscrew.